1994 3406 5EK

Most Cats run about 10 lbs higher than Detroit. Your RPMs look pretty high. 50 lbs at 1500 RPMs should be good. I may be wrong, haven’t had a Cat in 20 yrs. Looks like you’ve got plenty pressure. Doesn’t matter loaded empty or bobtail. Water temp looks good. Higher water temp will affect oil temp, and lower the pressure. I think a pressure reading at idle, normal operating temp will tell more of a story. Low pressure especially at idle being an indicator of worn bearings. Thats my understanding anyway.

 

Starting cold should run up to 70-80

At temp and running 50-60 is pretty normal

Would be worried if pressure drops under 20-25 at idle warmed up.

 

I would check the accuracy of that gauge, 75psi hot, at those rpm’s is too high according to what engineers have claimed over the years. Believe it or not but, too high of oil psi can cut into your mpg’s.
And it may be a signal someone may have gone into the engine and adjusted the oil pump, to hide a worn engine.

 

Looks more like 65 psi to me. Probably be 60 at 1500 RPMs.

 

That Guage is reading about 52-53 psi.

It's in spec but a little on the low side. Most E models are right around 60 psi at cruise down the hwy.

 

In my opinion, it should be over 60 at that rpm

 

Dash gauge is more or less an "estimate" if you want to know for sure you should put a proper test gauge into the main oil galley.

 

I see clearly now 52-53. Lol. Oops!

 

Verify pressure before anything.